1. Field of the Invention
The invention relates to a valve cartridge having a valve stack-up comprising a rotating ceramic disk and a fixed ceramic disk, both with pass-through openings that are brought into alignment to control the flow of fluid through the valve; and, more particularly, to a valve cartridge having reduced tolerance variations between the stack-up elements to better control the tight seal between the ceramic disks while permitting their rotation.
2. Description of the Related Art
Fluid valves using ceramic valve stacks comprising a fixed ceramic disk and a rotating ceramic disk, both of which have pass-through openings that are aligned and unaligned to control the flow of fluid through the valve, are widely known and appear in various configurations, such as in-line valves, diverter valves, and hydrants, to name a few. Almost all ceramic valves comprise a xe2x80x9cstack-upxe2x80x9d that traditionally includes an O-ring, a fixed ceramic disk, a rotating ceramic disk, and a bearing in contact with the rotating ceramic disk. The stack-up is typically contained within a valve body, which defines the various inlets and outlets to the fluid sources.
For the ceramic valve to work properly, the fixed and rotating ceramic disks must be held together in compression with a pressure (the stack-up pressure) sufficient to prevent fluid from leaking between the interface of the disks while having a rotating force less than a predetermined value. Typically, the stack-up pressure is applied by securing a valve body holding the stack-up against a compression seat, or securing a retainer to the end of the valve body as disclosed in U.S. Pat. No. Re. 35,545. The rotating force is the force that a user must supply to the handle of the valve to rotate the rotating disk with respect to the fixed disk to turn the valve through its various operating positions. Although there is some subjectivity in the desired rotating force, the force must always remain low enough to permit the weakest of users to easily operate the valve.
Striking a balance between the required stack-up pressure to prevent the ceramic valve from leaking and the desired rotating pressure is a problem for all valves using a ceramic stack-up. The problem is exacerbated in that it is very difficult to control the tolerance variations of the ceramic disks during their manufacture. The variation in the ceramic disks can vary the stack-up pressure that is required for a particular pair of ceramic disks.
It is highly desirable to produce a ceramic valve that provides better control over the stack-up pressure to thereby provide better control over the stack-up pressure and the rotating pressure of the valve.
The invention relates to a valve cartridge for controlling the flow of fluid through a fluid conduit that fludily connects a fluid source to a fluid outlet. The valve cartridge comprises first and second valve body portions. The valve body portions define a flow passage fluidly connecting the fluid source to the fluid outlet when the valve cartidge is fluidly coupled to the fluid conduit. The first and second valve body portions define a longitudinal axis.
A first ceramic plate is mounted to the first body portion within the flow passage and with the longitudinal axis extending through the first plate such that the first ceramic plate is axially immovable relative to the first body portion. A second ceramic plate is mounted to the second body portion within the flow passage such that the second ceramic plate is movable along the longitudinal axis and maintained in an axially facing relationship with the first ceramic plate. Each of the first and second ceramic plates have pass-through openings and are movable relative to each other between a first position, where the pass-through openings are not aligned, and a fluid flow through the flow passage is prohibited, and a second position, where the pass-through openings are aligned to permit fluid flow through the flow passage. A biasing element is disposed between the second body portion and the second ceramic plate to bias the second ceramic plate against the first ceramic plate along the longitudinal axis.
Preferably, the valve cartridge further comprises a bearing disposed between one of the first or second body portions and the corresponding first or second ceramic plates. The bearing is in abutting relationship with the corresponding first or second plate to protect the one of the first and second body portions from the relative movement of the first and second ceramic plates. The second body portion can have a bottom wall against which the second ceramic plate abuts and the bottom wall forms the bearing.
At least one channel is formed in the bottom wall and the biasing element is preferably a resilient seal disposed within the at least one channel to seal the second ceramic plate relative to the second body portion and to bias the second ceramic plate against the first ceramic plate. The resilient seal is preferably an O-ring and the second body portion pass-though opening is located in the bottom wall such that it is circumscribed by the O-ring.
The first body portion can comprise a top wall and an annular wall that depends from the top wall. The top wall and annular wall define a recess that is sized to receive the first ceramic plate to form a first valve seat within which the first ceramic plate is retained. The second body portion comprises a collar that defines a portion of a recess sized to receive the second ceramic plate and forming a second valve seat in which the second ceramic plate is received. The collar is preferably sized such that it abuts the first ceramic plate to bias the first ceramic seat within the first valve seat to compressibly retain the first ceramic plate against the top wall. Alternatively, the first body portion can comprise a radially extending lip that retains the first ceramic plate within the first body recess.
The collar has an upper end that is approximately coterminous with an upper surface of the second ceramic plate. The depth of the second body portion recess is approximately equal to the thickness of the second ceramic plate.
The collar has at least one notch formed therein and the second ceramic plate has a key extending through the notch wherein the second ceramic plate is moved between the first and second positions between the ends of the notch. Preferably, the collar comprises two diametrically opposed notches and the second ceramic plate has two diametrically opposed keys. The valve cartridge further comprises an outer collar circumscribing the second body portion having keyholes that receive the second ceramic plate key, wherein the rotation of the outer collar moves the second ceramic plate.
The first body portion preferably further comprises at least one key extending into the first body portion recess and the first ceramic plate having a keyhole sized to receive the key when the first ceramic plate is received within the recess to fix the rotational position of the first ceramic plate relative to the first body portion.
Preferably, the first and second ceramic plates are disks. The first and second body portions and the first and second ceramic disks can have multiple fluid openings that permit the rotation of the disks between a first position where fluid flow through the valve cartridge is prohibited, a second position where fluid flow through the valve cartridge is permitted, and a third position where fluid flow through the valve cartridge is bypassed through a filter element.
The biasing device is preferably made from a resilient material. The characteristics of the resilient material are selected to control the force supplied by the bypassing element to the second ceramic plate. Preferably, the hardness and size of the resilient material are the selected and controlled characteristics. The biasing element is preferably an O-ring seal.
Preferably, the first ceramic plate is located at a fixed position along the longitudinal axis independent of the position of the second ceramic plate along the longitudinal axis.